Acid Rain

Published on 05 Apr 2025

Acid rain is a term used to describe precipitation, such as rain, snow, fog, or other forms of precipitation, that has an abnormally low pH. This is mostly due to human activity releasing nitrogen oxides (NOx) and sulphur dioxide (SO2) into the atmosphere.

Causes of acid rain

• Combustion of Fossil Fuels: Combustion of fossil fuels such as natural gas, coal releases nitrogen oxides and sulphur dioxide into the atmosphere.

• Ultra-low sulphur diesel (ULSD) contains about 10 to 15 parts-per-millions of sulphur.

• Land use changes: Acid rain effects may be exacerbated by changes in land use, such as deforestation, which can change the natural balance of chemicals in the soil and water.

• Burning of biomass and agricultural residues: Burning of biomass and agricultural residues results in high emissions of Sulphur dioxide which later turns into acid rain.

• Example: Forest fire causing steady rise in Sulphur dioxide level in Srinagar Garhwal valley (Hemwati Nandan Bahuguna Garhwal University)

• Industrial activities: Chemical manufacturing, metal smelting and refining, paper production also play a role in emissions of nitrogen oxides and sulphur dioxides.

• Example:  Acid Rain from Industrial Activities like smelting of nickel ore in the Sudbury Region, Canada

• Volcanic eruptions: Volcanic smog containing toxic elements act as a source of acid rain.

• Example: Acid rain in Hawaii after the eruption of Kilauea

Effects of Acid rain

• Soil degradation: Acid rain leaches aluminium from the soil and reduces the soil pH. It also removes minerals and nutrients from the soil that trees need to grow.

• Example: Extensive soil acidification happened in the highly polluted "Black Triangle" in Central Europe

• Impact on buildings and monuments: Acid rain can hasten the corrosion of limestone, marble, concrete, and metal buildings, monuments, and infrastructure.

• Example: Marble cancer of Taj mahal

• Impact on trees: Acid rain causes deficiency of vital nutrients in soil resulting in less fertile degradation of the plant communities by acid rain can include damage to leaves, loss of productivity.

• Example: In the 1970s and ’80s, forested areas in central Europe, southern Scandinavia, and eastern North America showed alarming signs of forest dieback and tree mortality due to acid rain.

• Impact on lakes and rivers: The acid accumulation in lakes and rivers disrupts the reproductive processes of aquatic animals.

• Example: In 1980s Sulphur emissions from coal-burning power stations in Britain were impacted as weak sulphuric acid into lakes and rivers in Norway and Sweden which killed many aquatic lives.

• Impact on human health: Acid rain may cause irritation in the eyes, reduced visibility and disorders in the respiratory system in humans.

International initiatives

• Convention on Long Range Transboundary Air Pollution,1979: Multilateral agreement addressing transboundary air pollution, created a regional framework applicable to Europe, North America and Russia and former East Bloc countries for reducing transboundary air pollution.

• Gothenburg Protocol to LRTAP: To address pollutants that cause acidification and ground-level ozone. It limits on air pollutants including sulphur dioxide, nitrogen oxide, ammonia and volatile organic compounds

Way Forward

• Control over pollution: Establish and maintain strong emission standards for industries, power plants, and vehicles. Several emission-reducing equipment like scrubbers, electrostatic precipitators, etc. can be used for reducing air pollution.

• Neutralizing Agent: Increasing the pH of acidified water by adding a neutralizing chemical is a crucial step in mitigating the effects of acid rain.

• Multi-stakeholder approach: Controlling acid rain requires communities, local government and international participation. Laws should be formulated by the government to regulate emissions.

Encouraging Public awareness: Increasing public awareness about the issues of acid rain is the first step toward finding some solutions to the problem of acid rain.

Tags:
Environment

Keywords:
Air pollution Pollution Water pollution Climate change Acid rain

Syllabus:
General Studies Paper 3

Topics:
Environment and Climate Change